The present invention relates to an after-burning preventive and flame-out apparatus for an internal combustion engine.
In the operation of a vehicle having an internal combustion engine mounted thereon, the engine is in such a state that it is prone to an accidental fire immediately after either running on a long sloping road, sudden speed reduction, racing, or gear change, and the said state might possibly result in after-burning in some cases. Besides, in general practice, a certain quantity of a live gas is suctioned into the engine due to the continuation of the motion of the engine by inertia, and is exhausted thereafter in the form of a non-ignited gas, through an exhaust system, even after the engine is switched off. Therefor, in case a heat source (hot spot) as is sufficient to ignite the live gas is present, such a live gas as ought to be exhausted as a non-ignited gas through the exhaust system is subjected to combustion in the exhaust system, to thus result in explosive after-burning. The flame that results from said explosive after-burning reaches as far as the live gas that fills the entirety of the exhaust system, especially as far as the live gas that stagnates in the main muffler, thus being subjected to explosive combustion, until the pressure is raised, whereby the gas is caused to be exhausted through the outlet of the exhaust system at the speed well equivalent to the acoustic velocity, and this has thus far constituted such a series of defects as affect in a harmful manner the respective sections of a vehicle having an internal combustion engine mounted thereon as well as the environment outside the vehicle, as well as the exhaust system itself. To put it otherwise, such explosive after-burning often generates a quite high level of knocking, so also does it give off sparks out of a tail pipe at the outlet of the exhaust system in some case, which has thus far constituted a hazard.
Introduced to date as the methods of preventing the after-burning of this category have been: (1) means for causing a non-ignited gas mixture as is discharged from an engine to be subjected to combustion in an upstream section of a sound deadening apparatus, (2) means that subjects either an exhaust manifold or a thermal reactor to cooling in a proper manner to thus keep a non-ignited gas mixture free from being subjected to spontaneous ignition, and (3) means providing that, in case explosion should take place in the course of running of a non-ignited gas mixture through the exhaust system of a sound deadening apparatus, the flame and/or the explosive sound resulting thereby are so controlled as to be properly extinguished and/or deadened by means of a flaming-out apparatus and/or a sound deadening apparatus at the outlet of an exhaust pipe. The present invention relates to the third one of the methods set forth above. One of the conventional methods similar to that being introduced herein and presently available is such wherein, either a wire mesh, a filter, or the like is arranged in place at the outlet of an exhaust pipe. However the prior art method is not specifically designed for the purpose of effectuating flame-out but is designed for the purpose of preventing red-hot sparks of carbon from being scattered around, and the mesh of a wire mesh is required to be so formed as to be fine enough. This prior art method still involves such a series of inherent defects that the mesh is prone to be subjected to clogging, and, in case non-ignited gas mixture should be subjected to explosion in a sound deadening apparatus, a quite intensive flame is jetted out, which has hitherto made it difficult to prevent after-burning in a proper manner.